An unknown was prepared with the concentration of 0.000520 M. A Beer's Law plot was prepared using the absorbance values from standard solutions of ASA and a line drawn through all the points passed through the origin with a slope of 1550.2 M–1. The expected absorbance and %T values for the diluted aspirin solutionprepared by the student is ?

1 answer

If you plot A vs c, and remember the slope, it will be A/c but you know A=ebc. Since slope = A/c, that means the slope is e*b (where e = epsilon = molar absorptivity, sometimes called molar extinction coefficient). Thus, substitute c (0.000520M) and 1550.2 for e*b and calculate A which gives you the expected absorbance. Then A = log 1/T for T, multiply by 100 for %T.